The invention relates to an undersea communications cable which may be described more particularly as a cable containing optical fibers.
Coaxial undersea communications cables have been manufactured and deployed in analog telecommunications systems. In designing those cables, it has been necessary to overcome some obvious environmental factors such as low temperature, high compressive pressure and corrosive water. Additionally it has been necessary to design undersea cables to withstand large tensile and bending stresses encountered during cable laying and recovery operations.
Recent advances in the field of optical fiber communications technology have made possible some practical optical fiber communications systems. The characteristics of these systems, such as digital format, wide bandwidth and long repeater spacings, lead to what appears to be a relatively low cost per channel mile. This potential low cost makes an undersea communications cable containing optical fibers an attractive alternative to present day analog coaxial communications cables.
Heretofore, an undersea communications cable containing optical fibers was described in U.S. Pat. No. 4,156,104, issued to R. C. Mondello. Such cable included a central filament and stranded steel wires separated from the central filament by a core in which the fibers are embedded.
A problem arises in the design and fabrication of a cable including optical fibers for use in an undersea communication system. The measured loss of the optical fibers included in the cable has been dependent upon strain in the cable. Any large fluctuations in loss caused by strain in the cable during manufacture, deployment, or operation of the cable system complicate the processes of starting up, lining up and operating the undersea communication system.